cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-10 of 46 results. Next

A108741 Member r=100 of the family of Chebyshev sequences S_r(n) defined in A092184.

Original entry on oeis.org

0, 1, 100, 9801, 960400, 94109401, 9221760900, 903638458801, 88547347201600, 8676736387298001, 850231618608002500, 83314021887196947001, 8163923913326692803600, 799981229484128697805801, 78389996565531285692164900, 7681419682192581869134354401, 752700738858307491889474566400
Offset: 0

Views

Author

Henry Bottomley, Jun 22 2005

Keywords

Comments

Partial sums of A046173. [Joerg Arndt, Jun 10 2013]

Crossrefs

Programs

  • Magma
    I:=[0,1,100]; [n le 3 select I[n] else 99*Self(n-1)-99*Self(n-2)+Self(n-3): n in [1..20]]; // Vincenzo Librandi, Feb 02 2016
  • Mathematica
    LinearRecurrence[{99, -99, 1}, {0, 1, 100}, 20] (* Vincenzo Librandi, Feb 02 2016 *)

Formula

a(n) = ((49+20*sqrt(6))^n+(49-20*sqrt(6))^n -2)/96 = 98*a(n-1)-a(n-2)+2 = 99*a(n-1)-99*a(n-2)+a(n-3) = (a(n-1)-1)^2/a(n-2) = A004189(n)^2.
G.f.: -x*(x+1)/((x-1)*(x^2-98*x+1)). [Colin Barker, Oct 24 2012]
From Wolfdieter Lang, Feb 01 2016: (Start)
a(n) = (T(n, 49) - 1)/48 = (T(2*n, 5) - 1)/48 with Chebyshev's T polynomials A053120. See the name.
a(n) = A000217((T(n, 5) - 1)/2)/3. n >= 0.
a(n) = S(n-1, 10)^2 = A004189(n)^2, with Chebyshev's S polynomials A049310. This is the triangular number = 3*square number identity. Cf. the famous triangular number = square number identity: A000217((T(n, 3) - 1)/2) = S(n-1, 6)^2. A001109 and A001110. (End)

A098301 Member r=16 of the family of Chebyshev sequences S_r(n) defined in A092184.

Original entry on oeis.org

0, 1, 16, 225, 3136, 43681, 608400, 8473921, 118026496, 1643897025, 22896531856, 318907548961, 4441809153600, 61866420601441, 861688079266576, 12001766689130625, 167163045568562176, 2328280871270739841, 32428769152221795600, 451674487259834398561
Offset: 0

Views

Author

Wolfdieter Lang, Oct 18 2004

Keywords

Comments

Also m such that (3*m^2 + m)/4 = m*(3*m + 1)/4 is a perfect square. - Ctibor O. Zizka, Oct 15 2010
Consequently A049451(k) is a square if and only if k = a(n). - Bruno Berselli, Oct 14 2011

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{# - 1, -# + 1, 1}, {0, 1, #}, 20] &[16] (* Michael De Vlieger, Feb 23 2021 *)
  • PARI
    concat(0, Vec(x*(1+x)/((1-x)*(1-14*x+x^2)) + O(x^50))) \\ Colin Barker, Jun 15 2015

Formula

a(n) = (T(n, 7)-1)/6 with Chebyshev's polynomials of the first kind evaluated at x=7: T(n, 7) = A011943(n) = ((7 + 4*sqrt(3))^n + (7 - 4*sqrt(3))^n)/2; therefore: a(n) = ((7 + 4*sqrt(3))^n + (7 - 4*sqrt(3))^n - 2)/12.
a(n) = A001353(n)^2 = S(n-1, 4)^2 with Chebyshev's polynomials of the second kind evaluated at x=4, S(n, 4):=U(n, 2).
a(n) = 14*a(n-1) - a(n-2) + 2, n >= 2, a(0)=0, a(1)=1.
a(n) = 15*a(n-1) - 15*a(n-2) + a(n-3), n >= 3.
G.f.: x*(1+x)/((1-x)*(1 - 14*x + x^2)) = x*(1+x)/(1 - 15*x + 15*x^2 - x^3) (from the Stephan link, see A092184).
Conjecture: 4*A007655(n+1) + A046184(n) = A055793(n+2) + a(n+1). - Creighton Dement, Nov 01 2004
a(n) = (A001075(n)^2-1)/3. - Parker Grootenhuis, Nov 28 2017

A098296 Member r=11 of the family of Chebyshev sequences S_r(n) defined in A092184.

Original entry on oeis.org

0, 1, 11, 100, 891, 7921, 70400, 625681, 5560731, 49420900, 439227371, 3903625441, 34693401600, 308336988961, 2740339499051, 24354718502500, 216452127023451, 1923714424708561, 17096977695353600, 151949084833473841
Offset: 0

Views

Author

Wolfdieter Lang, Oct 18 2004

Keywords

Programs

  • GAP
    a:=[0,1,11];; for n in [4..30] do a[n]:=10*a[n-1]-10*a[n-2]+ a[n-3]; od; a; # G. C. Greubel, May 24 2019
  • Magma
    I:=[0,1,11]; [n le 3 select I[n] else 10*Self(n-1)-10*Self(n-2) + Self(n-3): n in [1..30]]; // G. C. Greubel, May 24 2019
    
  • Mathematica
    LinearRecurrence[{10,-10,1},{0,1,11},30] (* Harvey P. Dale, Jan 27 2012 *)
  • PARI
    my(x='x+O('x^30)); concat([0], Vec(x*(1+x)/((1-x)*(1-9*x+x^2)))) \\ G. C. Greubel, May 24 2019
    
  • Sage
    (x*(1+x)/((1-x)*(1-9*x+x^2))).series(x, 30).coefficients(x, sparse=False) # G. C. Greubel, May 24 2019
    

Formula

a(n) = 2*(T(n, 9/2)-1)/7 with twice Chebyshev's polynomials of the first kind evaluated at x=9/2: 2*T(n, 9/2) = A056918(n) = ((9 + sqrt(77))^n + (9 - sqrt(77))^n)/2^n.
a(n) = 9*a(n-1) - a(n-2) + 2, n >= 2, a(0)=0, a(1)=1.
a(n) = 10*a(n-1) - 10*a(n-2) + a(n-3), n >= 3, a(0)=0, a(1)=1, a(2)=11.
G.f.: x*(1+x)/((1-x)*(1-9*x+x^2)) = x*(1+x)/(1-10*x+10*x^2-x^3) (from the Stephan link, see A092184).

A098297 Member r=12 of the family of Chebyshev sequences S_r(n) defined in A092184.

Original entry on oeis.org

0, 1, 12, 121, 1200, 11881, 117612, 1164241, 11524800, 114083761, 1129312812, 11179044361, 110661130800, 1095432263641, 10843661505612, 107341182792481, 1062568166419200, 10518340481399521, 104120836647576012
Offset: 0

Views

Author

Wolfdieter Lang, Oct 18 2004

Keywords

Crossrefs

Programs

  • GAP
    a:=[0,1,12];; for n in [4..30] do a[n]:=11*a[n-1]-11*a[n-2]+ a[n-3]; od; a; # G. C. Greubel, May 24 2019
  • Magma
    I:=[0,1,12]; [n le 3 select I[n] else 11*Self(n-1)-11*Self(n-2) + Self(n-3): n in [1..30]]; // G. C. Greubel, May 24 2019
    
  • Mathematica
    LinearRecurrence[{11,-11,1}, {0,1,12}, 30] (* G. C. Greubel, May 24 2019 *)
  • PARI
    my(x='x+O('x^30)); concat([0], Vec(x*(1+x)/((1-x)*(1-10*x+x^2)))) \\ G. C. Greubel, May 24 2019
    
  • Sage
    (x*(1+x)/((1-x)*(1-10*x+x^2))).series(x, 30).coefficients(x, sparse=False) # G. C. Greubel, May 24 2019
    

Formula

a(n) = (T(n, 5)-1)/4 with Chebyshev's polynomials of the first kind evaluated at x=5: T(n, 5) = A001079(n) = ((5 + 2*sqrt(6))^n + (5 - 2*sqrt(6))^n)/2.
a(n) = 10*a(n-1) - a(n-2) + 2, n >= 2, a(0)=0, a(1)=1.
a(n) = 11*a(n-1) - 11*a(n-2) + a(n-3), n >= 3, a(0)=0, a(1)=1, a(2)=12.
G.f.: x*(1+x)/((1-x)*(1-10*x+x^2)) = x*(1+x)/(1-11*x+11*x^2-x^3) (from the Stephan link, see A092184).
a(n) = A132596(n) / 2. - Peter Bala, Dec 31 2012

A098306 Unsigned member r=-6 of the family of Chebyshev sequences S_r(n) defined in A092184.

Original entry on oeis.org

0, 1, 6, 49, 384, 3025, 23814, 187489, 1476096, 11621281, 91494150, 720331921, 5671161216, 44648957809, 351520501254, 2767515052225, 21788599916544, 171541284280129, 1350541674324486, 10632792110315761, 83711795208201600
Offset: 0

Views

Author

Wolfdieter Lang, Oct 18 2004

Keywords

Comments

((-1)^(n+1))*a(n) = S_{-6}(n), n>=0, defined in A092184.
This sequence is a divisibility sequence, i.e., a(n) divides a(m) whenever n divides m. Case P1 = 6, P2 = -16, Q = 1 of the 3 parameter family of 4th-order linear divisibility sequences found by Williams and Guy. - Peter Bala, Mar 25 2014

Crossrefs

Programs

  • Mathematica
    a[n_] := 1/10*((4 + Sqrt[15])^n + (4 - Sqrt[15])^n - 2*(-1)^n) // Simplify; Table[a[n], {n, 0, 20}] (* Jean-François Alcover, Apr 28 2017 *)
    LinearRecurrence[{7, 7, -1}, {0, 1, 6, 49, 384, 3025}, 50] (* G. C. Greubel, Aug 08 2017 *)
  • PARI
    x='x+O('x^50); Vec(x*(1-x)/((1+x)*(1-8*x+x^2))) \\ G. C. Greubel, Aug 08 2017

Formula

a(n) = (T(n, 4)-(-1)^n)/5, with Chebyshev's polynomials of the first kind evaluated at x=4: T(n, 4)=A001091(n)=((4+sqrt(15))^n + (4-sqrt(15))^n)/2.
a(n) = 8*a(n-1) - a(n-2) + 2*(-1)^(n+1), n>=2, a(0)=0, a(1)=1.
a(n) = 7*a(n-1) + 7*a(n-2) - a(n-3), n>=3, a(0)=0, a(1)=1, a(2)=6.
G.f.: x*(1-x)/((1+x)*(1-8*x+x^2)) = x*(1-x)/(1-7*x-7*x^2+x^3) (from the Stephan link, see A092184).
From Peter Bala, Mar 25 2014: (Start)
a(2*n) = 6*A001090(n)^2; a(2*n+1) = A070997(n)^2.
a(n) = |u(n)|^2, where {u(n)} is the Lucas sequence in the quadratic integer ring Z[sqrt(-6)] defined by the recurrence u(0) = 0, u(1) = 1, u(n) = sqrt(-6)*u(n-1) - u(n-2) for n >= 2.
Equivalently, a(n) = U(n-1,sqrt(-6)/2)*U(n-1,-sqrt(-6)/2), where U(n,x) denotes the Chebyshev polynomial of the second kind.
a(n) = 1/10*( (4 + sqrt(15))^n + (4 - sqrt(15))^n - 2*(-1)^n ).
a(n) = the bottom left entry of the 2 X 2 matrix T(n, M), where M is the 2 X 2 matrix [0, 4; 1, 3] and T(n,x) denotes the Chebyshev polynomial of the first kind.
See the remarks in A100047 for the general connection between Chebyshev polynomials of the first kind and 4th-order linear divisibility sequences. (End)

A098308 Unsigned member r=-8 of the family of Chebyshev sequences S_r(n) defined in A092184.

Original entry on oeis.org

0, 1, 8, 81, 800, 7921, 78408, 776161, 7683200, 76055841, 752875208, 7452696241, 73774087200, 730288175761, 7229107670408, 71560788528321, 708378777612800, 7012226987599681, 69413891098384008, 687126683996240401
Offset: 0

Views

Author

Wolfdieter Lang, Oct 18 2004

Keywords

Comments

((-1)^(n+1))*a(n) = S_{-8}(n), n>=0, defined in A092184.

Programs

  • Mathematica
    LinearRecurrence[{9,9,-1},{0,1,8},40] (* Harvey P. Dale, Aug 11 2013 *)

Formula

a(n)= (T(n, 5)-(-1)^n)/6, with Chebyshev's polynomials of the first kind evaluated at x=5: T(n, 5)=A001079(n)=((5+2*sqrt(6))^n + (5-2*sqrt(6))^n)/2.
a(n)= 10*a(n-1)-a(n-2)+2*(-1)^(n+1), n>=2, a(0)=0, a(1)=1.
a(n)= 9*a(n-1) + 9*a(n-2) - a(n-3), n>=3, a(0)=0, a(1)=1, a(2)=8.
G.f.: x*(1-x)/((1+x)*(1-10*x+x^2)) = x*(1-x)/(1-9*x-9*x^2+x^3) (from the Stephan link, see A092184).
a(x)=1/12(2*(-1)^x+(5+2*Sqrt[6])(5-2*Sqrt[6])^x+(5-2*Sqrt[6])(5+2*Sqrt[6])^x). - Harvey P. Dale, Aug 11 2013
a(n-1)+a(n) = A072256(n). - R. J. Mathar, Feb 19 2017

A098298 Member r=13 of the family of Chebyshev sequences S_r(n) defined in A092184.

Original entry on oeis.org

0, 1, 13, 144, 1573, 17161, 187200, 2042041, 22275253, 242985744, 2650567933, 28913261521, 315395308800, 3440435135281, 37529391179293, 409382867836944, 4465682155027093, 48713120837461081, 531378647057044800, 5796451996790031721, 63229593317633304133
Offset: 0

Views

Author

Wolfdieter Lang, Oct 18 2004

Keywords

Crossrefs

Programs

  • GAP
    a:=[0,1,13];; for n in [4..30] do a[n]:=12*a[n-1]-12*a[n-2]+ a[n-3]; od; a; # G. C. Greubel, May 24 2019
  • Magma
    [n le 2 select n-1 else 11*Self(n-1)- Self(n-2) + 2: n in [1..30]]; // Vincenzo Librandi, Mar 06 2016
    
  • Mathematica
    LinearRecurrence[{12,-12,1},{0,1,13},30] (* Harvey P. Dale, May 11 2012 *)
    RecurrenceTable[{a[0] == 0, a[1] == 1, a[n] == 11 a[n-1] - a[n-2] + 2}, a, {n, 30}] (* Vincenzo Librandi, Mar 06 2016 *)
  • PARI
    concat(0, Vec(x*(1+x)/((1-x)*(1-11*x+x^2)) + O(x^25))) \\ Colin Barker, Mar 06 2016
    
  • Sage
    (x*(1+x)/((1-x)*(1-11*x+x^2))).series(x, 30).coefficients(x, sparse=False) # G. C. Greubel, May 24 2019
    

Formula

a(n) = 2*(T(n, 11/2) - 1)/9 with twice Chebyshev's polynomials of the first kind evaluated at x=11/2: 2*T(n, 11/2) = A057076(n) = ((11 + sqrt(117))^n + (11 - sqrt(117))^n)/2^n.
a(n) = 11*a(n-1) - a(n-2) + 2, n >= 2, a(0)=0, a(1)=1.
a(n) = 12*a(n-1) - 12*a(n-2) + a(n-3), n >= 3, a(0)=0, a(1)=1, a(2)=13.
G.f.: x*(1+x)/((1-x)*(1-11*x+x^2)) = x*(1+x)/(1-12*x+12*x^2-x^3) (from the Stephan link, see A092184).

A098299 Member r=14 of the family of Chebyshev sequences S_r(n) defined in A092184.

Original entry on oeis.org

0, 1, 14, 169, 2016, 24025, 286286, 3411409, 40650624, 484396081, 5772102350, 68780832121, 819597883104, 9766393765129, 116377127298446, 1386759133816225, 16524732478496256, 196910030608138849
Offset: 0

Views

Author

Wolfdieter Lang, Oct 18 2004

Keywords

Programs

  • Mathematica
    LinearRecurrence[{13, -13, 1}, {0, 1, 14}, 18] (* Michael De Vlieger, Feb 23 2021 *)

Formula

a(n) = (T(n, 6)-1)/5 with Chebyshev's polynomials of the first kind evaluated at x=6: T(n, 6)=A023038(n)= ((6+sqrt(35))^n + (6-sqrt(35))^n)/2.
a(n) = 12*a(n-1) - a(n-2) + 2, n>=2, a(0)=0, a(1)=1.
a(n) = 13*a(n-1) - 13*a(n-2) + a(n-3), n>=3, a(0)=0, a(1)=1, a(2)=14.
G.f.: x*(1+x)/((1-x)*(1-12*x+x^2)) = x*(1+x)/(1-13*x+13*x^2-x^3) (from the Stephan link, see A092184).

A098300 Member r=15 of the family of Chebyshev sequences S_r(n) defined in A092184.

Original entry on oeis.org

0, 1, 15, 196, 2535, 32761, 423360, 5470921, 70698615, 913611076, 11806245375, 152567578801, 1971572279040, 25477872048721, 329240764354335, 4254652064557636, 54981236074894935, 710501416909076521
Offset: 0

Views

Author

Wolfdieter Lang, Oct 18 2004

Keywords

Programs

  • Mathematica
    LinearRecurrence[{# - 1, -# + 1, 1}, {0, 1, #}, 18] &[15] (* Michael De Vlieger, Feb 23 2021 *)

Formula

a(n) = 2*(T(n, 13/2)-1)/11 with twice the Chebyshev polynomials of the first kind evaluated at x=13/2: 2*T(n, 13/2)=A078363(n)=((13+sqrt(165))^n + (13-sqrt(165))^n)/2^n.
a(n) = 13*a(n-1) - a(n-2) + 2, n>=2, a(0)=0, a(1)=1.
a(n) = 14*a(n-1) - 14*a(n-2) + a(n-3), n>=3, a(0)=0, a(1)=1, a(2)=15.
G.f.: x*(1+x)/((1-x)*(1-13*x+x^2)) = x*(1+x)/(1-14*x+14*x^2-x^3) (from the Stephan link, see A092184).

A098302 Member r=17 of the family of Chebyshev sequences S_r(n) defined in A092184.

Original entry on oeis.org

0, 1, 17, 256, 3825, 57121, 852992, 12737761, 190213425, 2840463616, 42416740817, 633410648641, 9458742988800, 141247734183361, 2109257269761617, 31497611312240896, 470354912413851825, 7023826074895536481
Offset: 0

Views

Author

Wolfdieter Lang, Oct 18 2004

Keywords

Programs

  • Mathematica
    LinearRecurrence[{# - 1, -# + 1, 1}, {0, 1, #}, 18] &[17] (* Michael De Vlieger, Feb 23 2021 *)

Formula

a(n) = 2*(T(n, 15/2)-1)/13 with twice the Chebyshev polynomials of the first kind evaluated at x=15/2: 2*T(n, 15/2)=A078365(n)= ((15+sqrt(221))^n +(15-sqrt(221))^n)/2^n.
a(n) = 15*a(n-1) - a(n-2) + 2, n>=2, a(0)=0, a(1)=1.
a(n) = 16*a(n-1) - 16*a(n-2) + a(n-3), n>=3, a(0)=0, a(1)=1, a(2)=17.
G.f.: x*(1+x)/((1-x)*(1-15*x+x^2)) = x*(1+x)/(1-16*x+16*x^2-x^3) (from the Stephan link, see A092184).
a(2*n+2) = 17*A078364(n)^2; a(2*n+1) = A161591(n+1)^2. - Klaus Purath, Aug 13 2025
Showing 1-10 of 46 results. Next